Wash the meat, dab dry, spread with mustard and turn in breadcrumbs. Heat oil in a pan. Fry the escalopes for 4 minutes on each side.
In the meantime wash and slice the tomatoes. Peel onion and cut into rings. Wash the lettuce and drain well. Take the escalope out and cut into strips. Roast the pita breads in a toaster.
Stir yoghurt, mayonnaise and lemon juice until smooth. Season with salt, pepper and 1 pinch of sugar. Fill bread pockets alternately with lettuce, tomatoes, onion and strips of escalope. Sprinkle with yoghurt dressing.